1. Field of the Invention
The present invention relates to a percussion tool such as an electric hammer or a hammer drill in which the axial direction of a motor is substantially perpendicular to that of a tool bit held by a tool holder, a motor housing is made of a hard material such as aluminum, and a tail cover is attached to the lower end of the motor housing.
2. Description of the Related Art
Conventionally, in an electric hammer or a hammer drill in which a motor is placed so that the axial direction of the motor is substantially perpendicular to that of a tool bit held by a tool holder, a motor housing is made of a hard material such as aluminum, and a tail cover is attached to the lower end of the motor housing, the tail cover is usually configured by a resin-made member for the purposes of, for example, reduction in weight and cost.
A motor housing has functions of supporting the shaft of a motor housed therein, and holding brushes which are to be in contact with a commutator of the motor, and is configured so that an opening is formed in a lower end side in order to improve the assembling property of the motor or the like. The opening is closed by a detachable tail cover.
In some of conventional electric hammers and hammer drills, a motor housing is formed by a molded product. In this configuration, however, the strength of the motor housing is so low that the motor housing is damaged or broken during a work. Therefore, a motor housing is formed by a molded product of a hard material such as aluminum in order to enhance the strength of the motor housing.
In a conventional percussion tool such as a above-described one, since a tail cover attached to a bottom face of a motor housing is formed by a resin-made member, the tail cover is often in contact with a work member, the ground, or the like during a work to be heavily damaged or worn. In some cases, the tail cover may be broken.
Particularly, a lower end portion of such a tail cover on the side of a tool bit is in contact with a work member, the ground, or the like with a higher probability to be damaged or worn.
When a chipping or crushing work is conducted in the state where a tail cover which is formed by a resin-made member as described above is in contact with a work member, the ground, or the like, the contacting portion of the tail cover is easily damaged, worn, or broken because the body of the percussion tool is vibrated in the axial direction of a tool bit by repercussion due to the percussive movement of the tool bit.
When the percussion tool body is dropped on the ground or the like, the tail cover collides against the ground or the like, whereby the resin-made tail cover is often broken.
In order to solve the problems discussed above, a tail cover which is formed by a pressed metal product in place of a molded product of low strength and wear resistance may be contemplated. In this case, reduction in weight and cost cannot be attained, the tail cover is hardly formed into a complex shape, and the shape of the motor housing and the like are restricted. Namely, there arises a further problem in that the degree of freedom in design of the tool body is reduced.